Diagnosis of student mastery or non-mastery of a set of skills (or attributes) can be done using cognitive diagnosis models. Before diagnosing the students, the skills need to be chosen and the appropriate model needs to be selected. In this talk, I will first introduce the process of deconstructing the domain of an introductory statistics course into a hierarchical arrangement of cognitive attributes. I will then introduce three models that can be used to ascertain examinee's diagnostic information: Item Response Theory (the Rasch Model), the Continuous Diagnosis Model, and the Fusion Model. After describing the assessment development process, I will conclude with preliminary diagnostic results from the three models.